Dispensers for flexible sheet material in the form of a web, such as paper towel, cloth towel, tissue and the like, are well known in the art. Certain types of sheet material dispensers are powered through some or all of a dispense cycle by a drive mechanism including one or more springs. In such dispensers, a dispense cycle is initiated when a user grasps and pulls the sheet material “tail” which is the sheet material end which extends out from the dispenser. Pulling of the tail causes movement of the sheet material to rotate a drive roller and energizes a spring or springs attached to the drive roller. The spring or springs then power rotation of the drive roller through completion of the dispense cycle. Rotation of the drive roller powers operation of a cutting mechanism carried on the drive roller to fully or partially sever the web. A relatively high spring force is required in order to power the drive roller and cutting mechanism to fully or partially sever the sheet material web to provide a single sheet for the user. Typically, a pull force of about two pounds or more is required to overcome the force applied to the drive roller by the spring or springs.
While these dispenser types are very effective for their intended purpose, there is opportunity for improvement. For example, the relatively high pull force required to rotate the drive roller to initiate a dispense cycle can cause a problem known as “tabbing.” Tabbing refers to a condition in which a small portion of the sheet material tail tears off in the user's hand. The small portion which is torn off of the tail is referred to as a “tab.” The tab includes insufficient material to meet the user's needs. And, the remaining tail extending from the dispenser may be inadequate for a user to grip to initiate a new dispense cycle, thereby potentially disabling the dispenser. Tabbing can be a particular problem if water transferred from the user's hands to the tail causes the sheet material to moisten and to tear when pulled.
Paper and sheet material conservation is increasingly important, both for cost and environmental reasons. Dispensers of the type described above can be repeatedly and immediately cycled to dispense multiple sheets of material to the user. The capability to repeatedly and immediately cycle the dispenser encourages excessive use of sheet material, thereby increasing cost and waste. Small amounts of sheet material saved during each use represent large cumulative savings over the operational life of the dispenser.
It may be desirable to lengthen or shorten the sheet material tail. For example, it may be desirable to adjust the length of the tail to make the tail easier to grasp depending on the height or position at which the dispenser is located on a wall or other support surface. It may be desirable to adjust the length of the tail based on the type of user anticipated to use the dispenser. For example, a longer tail may be desirable if the dispenser is to be installed in a rest room used primarily by small children. Dispensers of the type described above lack structure permitting the attendant to lengthen or shorten the tail extending from the dispenser housing.
It would be an advance in the art to provide improved sheet material dispensers for paper towel, tissue and other materials which would operate easily and require a minimal pull force on the sheet material tail to initiate a dispense cycle, which would facilitate and encourage sheet material conservation and which would be capable of tail length adjustment.